Power transmission mechanism



POWER TRANSMISSION MECHANISM Original Filed June 18, 1932 d 23 m w a 7'5r M w 55 92 i l P n 3 a: 0 w i r1 i: 9 iii In 9 f H M N l r N w k "w 3 iF0 INVENTOR n FRANK AHAYES ATTO R N EYS Patented July 5, 1938 UNITEDSTATES PATENT OFFICE Original application June 18, 1932, Serial No.618,054. Divided and this application January 21, 1938, Serial No.186,016. In Great Britain August 19, 1931 11 Claims.

The invention which forms the subject of my present application (adivision of my copending application Serial No. 618,054, filed June 18,1932) relates to power transmission mechanisms of the friction type,particularly friction transmissions in which power is transmitted from adriving shaft or other member to a driven shaft or other member throughthe instrumentality of friction disks having toroidal grooves andinterposed friction rollers cooperating therewith.

With mechanisms of the type indicated, the amount of power transmissibleto the load depends, other things being the same, upon the tractivefriction between the rollers and disks,

5 with the result that overload may cause slippage,

with resulting wear and damage. This may be obviated by making thepressure of the disks or races on the rollers great enough for theheaviest loads on the mechanism; but in that case the pressure isunnecessarily high for lighter loads, with resulting unnecessarily highstresses and losses. In my prior Patent No. 1,698,229, issued January 9,1929, I have disclosed a pressure means or device by which the tractivecontact pressure of the disks and rollers depends upon the load itselfand is thus varied in a desired correspondence therewith. In themechanism de the cam grooves or recesses, thereby causing the disks toexert greater pressure on the cooperating rollers. The mechanismreferred to is generally quite suitable in transmission mechanisms inwhich a single set of rollers is employed or in which a plurality ofsets of rollers transmit power in series. However, in mechanisms inwhich two sets of rollers are in parallel as regards power transmissionit is important that the speed-ratio (i. e., angular) positions of therollers of the two sets be equal. If not, one set of rollers will tendto drive the load at a speed different from that of the other set, withconsequent slippage and wear of the contacting surfaces.

The chief object of the present invention is therefore to provide, in atransmission mechanism in which two sets of rollers drive in parallel, apressure mechanism or device by which tractive pressures can be producedin a desired cor- 55 respondence with the load without causing anydilference in the speed-ratio positions of the sets of rollers. To thisand other ends the invention comprises the novel features andcombinations hereinafter described.

Referring to the accompanying drawing:

Fig. 1 is a longitudinal section illustrating an embodiment of theinvention as applied to a transmission mechanism in which two sets ofrollers, driving in parallel, are arranged in the same transverse plane.To avoid unnecessarily complicating the description of the invention Ihave not shown any means for varying the speed ratio of the transmissionmechanism. The preferred means for causing change of speed-ratioposition of the rollers by precession is shown in my copendingapplication above identified to which reference may be made for a fulldisclosure thereof.

Fig. 2 is a detail cross section on the plane indicated by the line 2-2of Fig. 1.

Fig. 3 is a detail sectional plan view on the plane indicated by theline 33 of Fig. 1.

In the drawing, four toroidally grooved disks are shown, designated I 5,l6, l1, l8, with interposed rollers 19', 20, 2|, of which rollers i9 and20 constitute one set, the other set being composed of roller 2| and one(not shown) between the observer and the plane of the figure. At one endof the apparatus the two-part shaft 23 is mounted in a ball bearing 21carried by the casing 28 and its cupped other end is supported by a ballbearing 29 on a stud 30 mounted in the adjoining end of the coaxialshaft 26. Disks or races I5 and I! are keyed on shaft part 23a and arethus in positive driving connection therewith but capable of relativeaxial movement thereon, and disks or races I6, I8, having toroidalgrooves or raceways, are rigidly fixed together in the encircling drum24 which is connected by a spider or cone 25 to shaft 26.

Rollers I9, 20 cooperate with disks or raceways l5, l8, and assumingthat disk 15 is the driving disk, driven by shaft 23, and assuming alsothat the rollers can revolve in planetary fashion around the disk axisand that disks I6 and I8 are held stationary or non-rotatable, it willbe seen that the rollers will revolve about the disk axis at an angularspeed depending, other conditions being constant, upon the angle of therollers to the disk axis or the planes of the parallel disks. Similarly,if the rollers are nonplanetary and disks l6 and I8 rotatable, thelatter will be rotated at a speed also depending upon the angularposition of the rollers. It will also be clear that disks I6 and I8 maybe the driving disks and disks [5 and I! the driven disks. One oranother of the three elements, namely, the race element composed ofdisks l5-ll, the race element composed of disks 6-18, and the rollerassembly composed of the two sets of rollers, must be stationary, thatis, must not revolve about the disk axis. The stationary element,Whichever it may be, then takes the reaction of the load and accordinglymay be conveniently termed the reaction element.

A certain minimum frictional engagement- (tractive friction) of thedisks and rollers is obtained by one or more spring washers 3| betweendisk I! and flange 3la of cup 32 on shaft 23a.

As stated above, the amount of power transmissible to the load depends,other conditions being the same, upon the friction between the rollersand the disks. The friction depends, in turn, upon the pressure of therollers and disks upon each other. If the pressure is always greatenough to prevent slippage "at the maximum load imposed on thetransmission mechanism it will be greater than necessary at lesserloads, with consequently high frictional losses. Accordingly the presentinvention provides a novel torqueloading construction or pressure devicewhich depends upon the load resistance, increasing as the latterincreases, and vice versa, though not necessarily in a strictly linearmanner. Further the construction is such that the pressure does notdepend upon angular movement of either disk I5 or I! relative to theother, and hence these disks may be rigidly connected together, as bykeying them both to shaft 23a, as shown in Fig. 1.

In the construction illustrated, the inner part 23a of the two-partshaft 23 is journaled at its outer end in the outer part 23b which isequipped with a cup 85 having teeth in its edge cooperating with teethon the periphery of a cam member or collar 86, rotatable and axiallymovable relative to shaft part 2301.. Threaded on the journal of thelatter is a ball thrust bearing 81 to limit leftward movement of cam 86and between the collar and the adjacent disk l5 are three or more balls88 working in cam grooves or depressions 89 in the collar (see Figs. 2and 3) and similar depressions 90 in the disk. Eiach groove deepensgradually from its ends to its central portion. From study of theconstruction described it will be seen that as the load on the mechanismincreases, the shaft part 231) (shaft 23 being assumed to be the drivingshaft) will run ahead of disks I5 and I1, and shaft-part 23a. As thisoccurs the balls 88 are rolled into shallower parts of the cooperatingdepressions or recesses 89, 9!

thus urging disk l5 toward the right, and cam collar 86 (and with itshaft 23a and disk ll) toward the left, thereby increasing the pressureof disks l5 and IS on rollers I9, 20, and the pressure of disks I6, H onthe rollers of the other set, of which one is shown at 2|. The frictionof these parts on each other is thus increased so that no slip of one onthe other can occur. It will be observed that the operation described isentirely automatic. If at any time the load reaction on shaft 23b isdecreased the lessened tendency of shaft 2300 to lag permits the ballstoroll back to deeper parts of the recesses, thereby decreasing thepressure exerted on the disks and rollers. In this way the pressure ofthe parts on each other is always proportional to the load. It will alsobe observed that in the action described there is no rotary movement ofdisk l5 relative to disk 11, or vice versa. This is an advantageousfeature, since such relative rotation would cause one set of rollers totend to drive the driven element at a different rate than the other set,with resulting slip and wear which would sooner or later cause seriousdamage. It is advantageous to have the pressure-producing mechanism atthe driving end of the apparatus but it may be positioned at the otherend if desired.

It is to be understood that the invention is not limited to theconstruction herein specifically illustrated but can be embodied inother forms without departure from its spirit as defined by the appendedclaims.

I claim:

1. In a power transmission mechanism of the friction disk and rollertype, the combination with power-transmitting elements having toroidalraceways one of said elements comprising a shaft and disks mountedthereon to prevent relative angular movement of the disks but permitrelative axial movement thereof, and a plurality of sets of rollerscooperating with said raceways; of a shaft coaxial with the first shaftand angularly movable relatively thereto, and a cam-and-bell pressuredevice associated with said shafts for transmission of powertherebetween and production of contact pressure between said frictionrollers and raceways.

2. In a power transmission mechanism of the friction disk and rollertype, the combination with an element comprising a shaft having coaxialinner and outer parts capable of angular movement relative to eachother, and coaxial disks mounted on the inner part of the shaft toprevent relative angular movement of the disks but permit relative axialmovement thereof; of means for transmitting power between the outer andinner parts of the shaft and pressing the disks toward each other inaccordance with relative angular movement of the parts of the shaft,comprising a cam rotatable in unison with the outer part of the shaftand having cam recesses, and rolling bodies in said cam recesses and inpower-transmitting connection with the inner part of the shaft.

3. In a power transmission mechanism, in combination, a driving element,a shaft, coaxial toroidally grooved disks mounted on the shaft toprevent relative angular movement of the disks but permit relative axialmovement thereof; a toroidally grooved driven element; a plurality ofsets of friction rollers cooperating with the grooves in the driving anddriven elements for transmission of power therebetween; a shaft coaxialwith the first mentioned shaft and angularly movable relatively thereto;a pressure cam coaxial with said disks and adjacent to one of the sameand connected with said coaxial shaft for rotation thereby, the camhaving cam recesses and rolling members cooperating with said camrecesses and with the adjacent disk to vary the pressure on the saidadjacent disk in accordance with relative angular movement of said diskand cam.

4. In a power transmission mechanism, in combination, an element havingtoroidal raceways, an element comprising coain'al disks having toroidalraceways; a shaft on which said disks are mounted to prevent relativeangular movement of the disks but permit relative axial movementthereof, one of said disks having cam recesses in its outer face; aplurality of sets of friction rollers cooperating with the said racewaysto drive one of said elements from the other; a shaft coaxial with andangularly movable relatively to the first shaft; a pressure camencircling the axis of said shafts and adjacent to one of the same andconnected with the second-mentioned shaft for rotation in unisontherewith; the cam having cam recesses; and rolling members cooperatingwith the recesses in the cam and adjacent disk to vary the pressure onthe said adjacent disk in accordance with relative angular movement ofsaid disk and cam caused by variation of load on the transmissionmechanism.

5. In a power transmission mechanism, in combination, driving and drivenelements having toroidal raceways, one of said elements comprisingcoaxial disks incapable of angular movement relative to each other butcapable of relative axial movement; a plurality of sets of frictionrollers cooperating with the raceways for transmission of power betweensaid elements; a shaft coaxial with said disks and angularly movablerelatively thereto; a pressure cam coaxial with said disks and adjacentto one of the same and connected with said shaft for rotation in unisontherewith, the cam having cam recesses; and rolling members cooperatingwith said cam recesses and with the adjacent disk to vary the pressureon the said adjacent disk in accordance with relative angular movementof said disk and cam.

6. In a power transmission mechanism, in combination, a driving element,a driven element, and a reaction element, one of said elementscomprising toroidally grooved coaxial disks incapable of angularmovement relative to each other but capable of relative axial movement,another of said elements being toroidally grooved, and another of saidelements comprising a plurality of sets of friction rollers cooperatingwith the grooves in the other elements; a shaft coaxial with said disksand 'angularly movable relatively thereto; a pressure cam coaxial-withsaid disks and adjacent to one of the same and connected with said shaftfor rotation in unison therewith, the cam having cam recesses; androlling members coopcrating with said cam recesses and with the adjacentdisk in accordance with relative angular movement of said disk and cam.

*7. In a frictional power transmitting mechanism, in combination, ashaft; two axially spaced coaxial toroidal races in positive drivingconnection with said shaft but capable of relative axial movement withrespect to one another; an independently rotatable toroidal race coaxialwith said two races; friction rollers in tractive engagement with saidraces; a thrust-receiving member on said shaft at one end and outside ofthe first mentioned races; and torque loading means disposed between thethrust member and the back of one of the first mentioned races andadapted to resolve a limited relative angular movement of the shaft andthe torque loading means into two forces one of which is directedaxially against the adjacent race.

8. In a frictional power transmitting mechanism, in combination, ashaft; two axially spaced coaxial toroidal races in positve drivingconnection with said shaft but capable of relative axial movement withrespect to one another; an independently rotatable toroidal race coaxialwith said two races; friction rollers in tractive engagement with saidraces; a thrust-receiving member on the shaft and outside of the races;torque loading means disposed between the thrust-receiving member andthe back of one of the first mentioned races and adapted to resolve alimited relative angular movement of the shaft and torque loading meansinto two forces one of which is directed axially against the adjacentrace, said means comprising a cam member around the shaft and rollingmembers cooperating therewith and with the adjacent race; and means forrotating the cam member to drive said axially movable races through saidrolling members.

9. In a friction power transmitting mechanism, in combination, a shaft;a second shaft in axial alignment therewith; two toroidal races mountedon the second shaft and incapable of rotational movement relative toeach other but capable of relative axial movement; an independently ro-V tatable toroidal race coaxial with the first two;

friction rollers in tractive connection with said races; a thrustbearing on the second shaft; torque loading means between the thrustbearing and the back of one of the first mentioned races and adapted toresolve a limited relative angular movement of the shaft and the torqueloading means into two forces, one of which is directed axially againstthe adjacent races; and rotation-transmitting means connecting the firstmentioned shaft and the torque loading means.

10. In a frictional power transmitting mechanism, in combination, ashaft; a cup on one end thereof; a second shaft coaxial with the firstand having an end extending into the cup; two toroidal races mounted onthe second shaft and incapable of rotational movement relative to eachother but capable of relative axial movement; a toroidal race coaxialwith said axially movable races; friction rollers having tractiveengagement with said races; torque loading means outside of the racesfor converting a limited relative angular movement of the second shaftand the torque loading means into two forces one of which is directedaxially against the adjacent race, the torque loading means comprising acam member connected with said cup, and rolling members cooperating withthe cam member and the adjacent race element; and a thrust bearing forthe cam member, mounted on the second shaft with the cup fortransmission of rotation therebetween; a thrust bearing mounted on thesecond shaft within the cup to cooperate with said cam collar; coaxialraces concentric with the second shaft and incapable of angular movementrelative to each other but capable of relative axial movement; anindependently rotatable race coaxial with the first mentioned races;friction rollers in tractive engagement with the races; and rollingbodies between the cam collar and the adjacent race for conversion ofrelative angular movement of the cam collar and the adjacent race intotwo forces one of which is directed axially against said adjacent race.

